Archive

Priapism Made Easy

Priapism Made Easy

Alan W. Shindel, Maurice M. Garcia, and Tom F. Lue

Department of Urology

University of California, San Francisco

February 2009

Diagnosis

Priapism is defined as a pathological condition of penile erection that persists beyond or is unrelated to sexual stimulation.[1] The first step in managing priapism is to determine whether or not the condition is ischemic veno-occlusive priapism or non-ischemic arterial priapism. Ischemic priapism may be conceived of as compartment syndrome of the penis secondary to obstruction of venous outflow. Ischemic priapism requires urgent intervention as the chance of ischemic damage and subsequent permanent fibrotic change of corporal tissue increases with delay in treatment. Non-ischemic priapism is most often secondary to traumatic rupture of a branch of the cavernous artery and uncontrolled pooling of blood into the sinusoidal spaces of the corpora cavernosa; this condition may be managed conservatively.

Consideration must be given to possible underlying causes for ischemic priapism. Sickle cell disease, thallasemia, and leukemia are blood conditions that have been associated with priapism; these conditions should be ruled out in the evaluation of a patient who presents with sustained erection. Other possible causes of ischemic priapism include medications with alpha antagonist activity (antipsychotics such as thioridazine, anti-depressants such as trazodone, and antihypertensives such as hydralazine or prazosin), illicit drugs (particularly cocaine), erectogenic drugs injected into the penis for the treatment of erectile dysfunction, and possibly exogenous androgens. Metastatic malignancy leading to obstruction of venous outflow tracts from the penis is a rare cause of priapism and typically presents in patients with advanced disease. Unfortunately, in many cases a specific cause for the disorder cannot be found and therefore no widely accepted specific therapy is available to prevent future recurrences.

A detailed history and physical exam usually suffices to determine the type of priapism, with non-ischemic priapism more common in patients with a semi-tumescent, painless erection and a history of trauma. Patients with ischemic priapism typically have significant pain and rigid erections. If there is any doubt, a penile blood gas determination by aspiration of corporal blood may determine if the penis is in an ischemic state. Aspiration of corporal blood for diagnosis may be performed as a step in irrigation and aspiration for treatment (see below). Aspiration of dark blood which is low in oxygen content and pH and high in carbon dioxide is indicative of ischemic priapism. Bright red blood which is high in oxygen and pH and has low carbon dioxide content is indicative of high-flow priapism. A complete blood count should be obtained on all patients who present with priapism. Other laboratory tests to consider include reticulocyte count, urinalysis, and urine toxicology.

Color duplex ultrasound may be considered as an adjunct diagnostic modality for priapism but it is not typically necessary except in cases where blood gas values were not diagnostic. It should be noted that color duplex ultrasound is a “real time” evaluation of blood flow and is more accurate than blood gas determination, which may take several hours to change even in complete absence of blood flow.

Treatment of ischemic priapism

While no definite “point of no return” for erectile function after priapism has been determined, studies indicate that priapism lasting longer than 24 hours is usually associated with various degree of erectile dysfunction.[2] Therefore, time is of the essence in the treatment of ischemic priapism.

If a specific cause for priapism is identified therapy should be directed towards the root cause. Transfusion, hydration, and oxygenation for priapism secondary to sickle cell disease was traditionally the management of choice for such patients but more recent evidence suggests that this regimen is unlikely to succeed and tends to delay effective therapy. In the case of malignant priapism treatment of the malignant process with radiation or chemotherapy may be helpful.[3] It is important to emphasize that treatment of the underlying condition should be administered concurrently with treatment directed at directly reversing priapism.[4]

It must be borne in mind that priapism can be a very litigious issue. The urologist must have a thorough and realistic discussion of treatments and prognosis with the patient, preferably with family and other witnesses present. Meticulous documentation of discussions and procedures must accompany these discussions.

Medical Treatments of ischemic priapism

Many patients with priapism are initially treated by emergency room staff with oral terbutaline or pseudoephrine. While these interventions are anecdotally effective strong evidence supporting their use is scant.

Patients should receive adequate analgesia as priapism may be very painful. Local analgesia in the form of a penile block is favored for the majority of patients. At our institution we favor a lidocaine/bupivicaine mix injected at the base of the phallus to provide both quick and prolonged anesthesia.

Evacuation of old blood is a simple intervention that often produces some detumescence and relief of pain. A 21 gauges or larger needle is inserted into the corpus cavernosum through the glans or the lateral aspect of the penis and the corpora are irrigated and aspirated with sterile normal saline. While this maneuver is often somewhat effective at reducing tumescence corporal irrigation/aspiration alone may not be sufficient to relieve priapism.

Intracavernous injection of alpha agonists is a mainstay in the treatment of priapism and is given after old blood is evacuated. Alpha agonists act by constriction of the cavernous arteries and contraction of smooth muscles around the sinusoids of the corpora. This leads to reopening of the sub-tunical and emissary veins. The alpha-1 selective agonist phenylephrine (0.5-1 mg/mL in normal saline) is the preferred agent because of its’ lack of beta adrenergic/cardiac effects. The most commonly accepted dosing of this drug is 0.5-1 mL every 5 minutes for up to one hour or detumescence. Caution should be exercised when alpha agonists are administered as significant rises in blood pressure may result from systemic vasoconstriction. This is of particular concern in patients with serious cardiovascular disease. Close monitoring of the patient’s subjective symptoms, blood pressure, and pulse should accompany this treatment.

Shunt Procedures

Shunting of blood from the corpus cavernosum to the corpus spongiosum, glans or alternative venous channels is an option of last resort in cases of severe refractory priapism. Three types of shunts have been described: distal, proximal and venous. Distal shunts permit direct blood flow from the corpus cavernosum to the glans and include the winters’ (with a biopsy needle), the Ebbohoj (with a # 11 knife), and the Al-Ghorab (surgical excision of the tip of corpus cavernosum through the glans). Proximal shunts create a connection between the proximal spongiosum and the corpora and include the Quackles (perineal approach) and the Sacher (penoscrotal approach). Venous shunts connect the corpora to a vein and include the Greyhack (corpora to saphenous vein) and the Barry (corpora to dorsal vein of penis).

At our institution we favor a distal T-shaped shunt with or without tunneling (The TT shunt). This is produced by insertion of a #10 blade scalpel through the glans and into the corpus cavernosum with the knife blade held in parallel to the urethra. Puncture is followed by a 90-degree lateral rotation of the blade away from the urethra so as to produce a T-shaped shunt between the glans and the corpus cavernosum when the knife is pulled out. The old blood is then evacuated and the wound closed with small absorbable sutures (e.g. 5-0 chromic continuous). We then observe the penis for 10 minutes to assure detumescence. If the penis becomes rigid again, the same procedure is repeated on the other side. In priapism of more than 3 days duration, distal shunt may not be effective due to thrombosis or severe edema of the erectile tissue. In these cases, we insert a 7 mm (21 Fr) straight sound through the T shunt to the base of the penis to create a “tunnel” which allows more effective evacuation of old blood as well as passage of arterial blood to the distal penis to keep the shunt open. This maneuver is repeated on the contra-lateral side. This procedure can be performed under local anesthesia in the emergency room or the clinic. We have successfully reversed priapism of up to 2 weeks duration with this technique. In these prolonged and very painful cases, the patient is made aware that the procedure is performed to relieve pain and impotence is inevitable.

In priapism of more than 2 days duration, the penis may not detumesce completely after a successful shunting procedure due to reactive hyperemia from tissue ischemia/death. Color duplex ultrasound is the preferred means of assessing response to shunting as it provides a real time measure of cavernosal blood flow; in successful shunt procedures flow will be high. If ultrasound is not available repeat penile blood gas assessment may be utilized, although this method is not as accurate as ultrasound because oxygen tension within the corpus cavernosum may take several hours to change even after successful intervention.

In over 90% of priapism cases lasting less than 24 hours the condition can be managed by intracavernous injection of alpha-agonists alone with complete recovery of baseline erectile ability. Some degree of ED can be expected when the duration of priapism is longer than 24 hours and a longer duration of tumescence is associated with worse prognosis. In cases of priapism of more than 3 days duration, the chance of complete recovery of erectile capacity is small.

Some authors have suggested that in patients with prolonged low-flow priapism a penile prosthesis should be implanted immediately.2 This intervention should be considered when there is little or no hope of recovery of normal erectile function. The theoretical advantage of this approach is the avoidance of prosthesis placement at a future time when there is a higher risk of complication from implantation in scarred, fibrotic corpora. If immediate prosthesis placement is elected a biopsy of the corpora should be obtained at the time of surgery to document irreversible fibrotic disease.

Treatment of non-ischemic priapism

Given that there is typically no ongoing ischemic damage in cases of high-flow priapism, conservative management with analgesics is the management of choice. In some cases the condition may spontaneously resolve.2 Hakim et al reported a series of patients with high flow priapism who elected to defer therapy and did well with no further management; these patients were able to attain erections sufficient for intercourse and appeared to suffer no negative sequlae.[5] For patients who demand intervention selective angioembolization of the fistulous tract with absorbable materials (autologous clot or gelfoam pledgets) is the management of choice. Worsening of erectile function, infection, and failure of embolization to reverse priapism are reported complications of this procedure.[6] Patients may be followed with repeat perineal Doppler ultrasounds to document resolution of the fistulous connection. In men with non-ischemic priapism of longer than 6 months duration, a pseudocapsule is formed around the ruptured artery. If definitive therapy is contemplated more than 6 months after onset of non-ischemic priapism and perineal ultrasound confirms the presence of a pseudocapsule, suture ligation of the ruptured artery and its’ pseudocapsule using intra-operative ultrasound guidance is a viable alternative treatment.

Prevention of recurrent “stuttering” priapism

Patients with frequent recurrent (“stuttering”) priapism represent a particular challenge. These patients may have weekly or even more frequent episodes of priapism that severely interfere with their life. Interventions for this type of recurrent problem include aggressive blockade of testosterone with ketoconazole (which requires supplementation of corticosteroids to prevent adrenal insufficiency), anti-androgens and LHRH agonists. These treatments are effective but exert a significant impact on the man’s libido and morning erections but not sexual erections. This treatment can be discontinued after 6 months and re-instituted if stuttering priapism recurs. Long term androgen suppression should be avoided in pre-pubertal patients.

An interesting novel therapy for priapism is low dose phosphodiaesterase type 5 inhibitors (PDE-5I). This counter-intuitive therapy has been championed by Burnett et al, who have recently introduced intriguing evidence to support the role of NOS/PDE 5 dysregulation as an important factor in the pathogenesis of priapism. Low dose daily PDE-5I treatment prevented recurrent priapism while preserving normal erectile function in a small series of patients, presumably by re-regulating PDE-5 activity.[7] Additional studies of this new therapeutic modality are needed. Currently, we prefer to use this therapy for pre-pubertal patients and those with sickle cell – related priapism.

Legends

Table 1. Synopsis of AUA Guidelines on Priapism

1.The first step is to differentiate ischemic vs. non-ischemic priapism

2.In patients with underlying etiology for ischemic priapism intracavernous treatment of priapism should not be delayed while treatment of the underlying condition is initiated

3.Initial intervention for ischemic priapism should include corporal irrigation/aspiration and/or injection of a sympathomimetic agent.

4.The sympathomimetic agent of choice is phenylephrine 100-500 mcg in 1 mL sterile saline every 3-5 minutes for up to one hour. Patients should be monitored for potentially serious hypertensive response.

5.Surgical shunts should be considered only after failure of corporal irrigation and sympathomimetic agents

6.Oral sympathomimetics have a very limited role in the treatment of ischemic priapism.

7.The initial management of choice for non-ischemic priapism is observation followed by selective angioembolization using absorbable materials if patient requests treatment.

8.Surgical therapy for high-flow priapism may be contemplated after at least 6 months and requires pre-operative and intraoperative ultrasound.

9.Androgen suppression is an option for the management of stuttering priapism but should not be continued long term in pre-pubescent patients.

10.Certain patients with stuttering priapism may be candidates for self-injection of sympathomimetic agents.